1. Field of the Invention
The present invention relates to a method for rendering a dye image resistant to light, and more particularly to a method for improving the light resistance of a dye image that is formed on a silver halide color photographic light-sensitive material.
2. Description of the Prior Art
As the generally applicable method for forming a dye image by use of a silver halide color photographic light-sensitive material there is known, as described in James et al, "The Theory of Photographic Process," 4th ed., 1977, a method for forming dyes by the reaction of photographic couplers with the oxidized product of a color developing agent, which method uses magenta, yellow and cyan couplers as the photographic couplers for ordinary color reproductions, and an aromatic primary amine-type color developing agent as the color developing agent, and in which the magenta and yellow couplers react with the oxidized product of the aromatic primary amine-type developing agent to form dyes such as azomethine dyes, and the cyan coupler reacts with the same oxidized product of the color developing agent to form a dye such as an indoaniline dye.
One of basically desired natures for the dye image formed by the reaction of the oxidized product of the color developing agent with the magenta, yellow and cyan photographic couplers is that these dyes be not discolored with age even when exposed over a long period to light or stored under high-temperature and highly moist conditions. Above all, since the resistance to light of a dye image formed from the magenta coupler has been unsatisfactory, adequate improvement in this aspect has long been awaited.
There have until now been many proposals for improving the light resistance of a dye image formed from a magenta coupler, which proposals include, for example, the use of a selected less-discolorable magenta coupler, the protection of a magenta dye image from ultraviolet rays by use of an ultraviolet-absorbing agent, the use of an antidiscoloration agent to prevent a magenta dye image from its discoloration by light, and incorporating a light resistance-providing radical into a magenta coupler.
Of these the method which uses an ultraviolet-absorbing agent requires a relatively large amount of an ultraviolet-absorbing agent in order to give a satisfactory light resistance to a resulting dye image. This method, however, has the disadvantage that the color of the ultraviolet-absorbing agent itself stains the magenta dye image area or margin area of a photographic sheet; or because the use of the ultraviolet-absorbing agent alone is not enough to prevent possible discoloration of the dye image due to visible rays the improvement of the magenta dye image in its resistance to light naturally has its limits.
As the method which uses an antidiscoloration agent there is known a method which uses an antidiscoloration agent having a phenolic hydroxyl radical or a radical that is hydrolyzed to produce a phenolic hydroxyl radical. As such the antidiscoloration agent, those compounds have been proposed which include, e.g., phenols and bisphenols; pyrogallol and gallic acid and esters thereof; .alpha.-tocopherols and acyl derivatives thereof; hydroquinone derivatives; 6-hydroxychromans; 5-hydroxychroman derivatives; 6,6'-hydroxy-2,2'-bis-spirochromans, and the like. These, however, are not considered to be capable of sufficiently preventing a magenta dye image from its possible discoloration.
Further, as another method for improving the light resistance of a magenta dye image, British Pat. No. 1,451,000 describes improvement of the stability of an organic light-absorbing compound by use of an azomethine light-cut compound having its maximum absorption wavelength on a longer wavelength side than the maximum wavelength of the above organic light-absorbing compound. In this method, however, the azomethine light-cut compound itself has a color, which varies the tone of the organic light-absorbing compound, so that it cannot be practically used for improving the light resistance of a dye image.
Japanese Patent Publication Open to Public Inspection (hereinafter referred to as Japanese Patent O.P.I. Publication) Nos. 67649/1975, 62826/1979, 62987/1979, 65185/1979, 69580/1979, 72780/1979, 82234/1979, 82385/1979 and 136581/1974 describe methods of improving the light resistance of a dye image by using metallic complexes. However, these particular metallic complexes described in these publications themselves have comspicuous colors which would adversely affect the color tone, color purity, whiteness of the white area, etc., of a resulting dye image, so that particularly in such a photographic element for direct appreciation use which attaches importance to aesthetics as, e.g., a dye image-bearing color photographic paper, etc., the use of such color degrading metallic complexes may bring about large defective troubles. These known metallic complexes, when added to the silver halide emulsion layer(s) constituting a silver halide color photographic light-sensitive material, tend to accelerate the deterioration of the characteristics (occurrence of desensitization, fog, etc.) of the silver halide emulsion. Further, these metallic complexes are disadvantageous in respect that they cannot be added in as much a quantity as required to obtain a sufficient antidiscoloration effect because they are generally less soluble in organic solvents.
Further, those metallic complexes as described in Japanese Patent O.P.I. Publication Nos. 99340/1981 and 168625/1981, although their adverse effect upon the characteristics of a silver halide emulsion is comparatively small, have their own color which still remain unsolved, so that they have the large disadvantage that they, when used in a photographic element for direct appreciation use, impair the beautifulness of a dye image. And certain metallic complexes, if used in a silver halide emulsion and when the emulsion is stored over an extensive period, deteriorate the light-resistant effect of and cause yellow stain on the emulsion.
As has been described above, these image dye's light resistance improving methods using the ultraviolet-absorbing agent, antidiscoloration agent or azomethine light-cut compound, although light-resistant effects can be expected to a certain extent from them, have the problem that the ultraviolet-absorbing agent's or azomethine light-cut compound's own color produces stain on resulting dye images. The method using metallic complexes, although an adequate light-resistant effect can be expected, is disadvantageous in respect of many such problems that the complex causes stain on resulting images due to its own color; deteriorates the photographic characteristics; is less soluble in solvents; and so forth. And some metallic complexes increase stain and deteriorate the light resistance-improving effect during a long-period storage. Accordingly, every metallic complex has some disadvantage, so that any metallic complex is not considered suitable for practical application. Thereupon, the realization of a method capable of attaining adequate light resistance of dye images by use of a novel metallic complex has been desired, the metallic complex being free from such the disadvantages as color stain, deterioration of photographic characteristics, less solubility, and increase in discoloration as well as in color stain during a long-period storage.